A conventional mechanical scanning 3D ultrasonic transducer, for example, an arc-shaped scan ultrasonic transducer, which swings an ultrasound transmitting/receiving unit of the ultrasonic transducer in a short-axis direction, includes a rotating disk (an optical rotating plate) at a driving member disposed in the middle of a mechanism to transmit a rotation of a drive motor shaft to the ultrasound transmitting/receiving unit. The mechanical scanning 3D ultrasonic transducer uses a transmission type photosensor to detect a rotation position of the ultrasound transmitting/receiving unit.
For example, as illustrated in FIG. 5A, a drawing of the conventional arc-shaped scan ultrasonic transducer, the arc-shaped scan ultrasonic transducer includes a case 31 in a housing 30. Holding plates 33 are disposed at both sidewalls on the case 31 to be freely swung by central axes 32. An ultrasound transmitting/receiving unit 34 constituted of a piezoelectric element group is disposed on a top surface portion of the holding plates 33.
A framing body 36 is fixedly secured to a lower surface portion of the case 31. A driving motor 35 is disposed on a lower surface of the framing body 36. A control shaft 39 is connected to a bevel gear mechanism 37, which is disposed inside the case 31, via a gear mechanism. The driving motor 35 causes the control shaft 39 to mesh with a bevel gear fixedly secured to one sidewall of the holding plate 33 to rotate the control shaft 39. Thus, the ultrasound transmitting/receiving unit 34 is swung in the short-axis direction.
As details are illustrated in FIG. 5C, a semilunar optical rotating plate 38 is connected to the control shaft 39 illustrated in FIG. 5A. A light shielding unit 38a and a light transmitting unit 38b are each formed at an interval of 180° in a direction opposite from one another from a rotational center of the optical rotating plate 38 with a boundary P as the reference.
A transmission type photosensor 40 is disposed on an internal surface of the framing body 36. The transmission type photosensor 40 detects an origin position of the ultrasound transmitting/receiving unit 34 in the short-axis direction to ensure obtaining biological information from an accurate position of a subject (a living body) (see Patent Document 1).
A linear scan ultrasonic transducer that reciprocates the ultrasound transmitting/receiving unit of the ultrasonic transducer illustrated in FIG. 5B in a direction parallel to a short-axis direction includes a moving mechanism 51. The moving mechanism 51, which is disposed on a side surface portion of a container body 50, is constituted of a timing belt and a drive pulley. The moving mechanism 51 is guided by a pair of linear guides 52, which are disposed at side surface portions of the container body 50, rotatably drives an electric motor 53, and reciprocates a transducer body (an ultrasonic transducer) 54 in the short-axis direction to perform a linear scan.
The linear scan ultrasonic transducer also swings the ultrasound transmitting/receiving unit in the short-axis direction to cause the ultrasound transmitting/receiving unit to perform the scan. Similar to the arc-shaped scan ultrasonic transducer, a transmission type photosensor (not illustrated) detects a right end portion (an R end) and a left end portion (an L end) in the movement of the ultrasound transmitting/receiving unit in the short-axis direction and detects an origin position to form a two-dimensional image of a subject. Subsequently, the linear scan ultrasonic transducer moves the ultrasound transmitting/receiving unit in the short-axis direction to form a three-dimensional image combined with this two-dimensional image. Thus, biological information can be obtained from an accurate position of the subject (the living body) (see Patent Document 2).